Glycosylidene Carbenes. Part 4. Synthesis of Spirocyclopropanes from Acetamidoglycosylidene-Derived Diazirines

✍ Scribed by Andrea Vasella; Christian Witzig; René Husi

• Publisher: John Wiley and Sons
• Year: 1991
• Tongue: German
• Weight: 760 KB
• Volume: 74
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19910740625

✦ Synopsis

o + o ~ BnO OBn En0 1 2 3 1363 4 5 Results and Discussion. -Preparation of the Aziallose 4. The synthesis of 4 follows the established method for the synthesis of l-azisugars [la] (see Scheme 2 ) . The allyl allopyranosides 10 are available from N-acetylglucosamine in four steps (6 -+ 7 [6] --+ 8 [7]

-+ 9 [8] --+ 10 [9]; 33% overall yield of the C X -D -~~) by following the strategy which was worked out by Jeanloz [9] for the synthesis of the corresponding methyl glycoside.

Benzylation (BnBr, BaO, Ba(OH), . 8H20, DMF) converted 10 in high yields into 11. The usual two-step procedure for the removal of the allyl group (KOBu'; HgC12, HgO) gave the crystalline hemiacetals 12 (89%). The oximes 13 were obtained in high yields ((E)/(Z) 4: 1). Oxidation of 13 with periodate gave the hydroximolactone 14, again in high yields. It was directly transformed into the triflate 15. Treatment of 15 with a soh. of H3N in MeOH yielded the diaziridines 162) (64%) which, upon oxidation with I2 in CH2C12 in the presence of Et,N, gave the crystalline diazirine 4 (87%). This product was stored at -20" for several weeks without significant decomposition. The triflate 15 is a more suitable starting material than the corresponding mesylate, which gave 16 in only 20% yield. The structures of 4 and 11-16 were confirmed by their spectroscopic data (see Tables and and Exper. Part).